The invention relates to automatic ice making machines, and more particularly to an evaporator frame used in automatic ice making machines and the method of manufacture of a two step molded evaporator frame.
Automatic cube ice machines generally comprise a refrigeration system (compressor, condenser and evaporator), a plurality of ice-formation pockets (usually in the form of a grid of cells) and a water supply system. The evaporator is that part of the ice-making machine that has water flowing over a grid on the front and is cooled on the back by refrigerant tubing. An evaporator pan forms part of the evaporator in an automatic ice-making machine. The evaporator pan is generally a stamped metal pan to which the grid and refrigerant tubing may be attached.
Evaporator pans and grids are generally nickel or tin plated copper. Commonly, the ice cube grids and other items, such as studs, were attached to the evaporator pan to make the evaporator. After assembly, the evaporator pan was plated with nickel or tin. In the past, the studs projected from the back side of a flange and were welded onto the evaporator pan. The studs corresponded to openings in an evaporator frame. These studs were inserted into the openings in the evaporator frame and secured to the same through the use of washers and nuts. One of the functions of an evaporator frame is to mount an ice forming evaporator in an ice-making machine.
In the past, the evaporator frame could be made from four (or more) separate plastic components; commonly one component for each side of the evaporator pan. In addition, a gasket was used in assembling and sealing the frame and evaporator pan. The gasket itself could also be constructed of four (or more) pieces. In the past, these at least eight pieces, the four plastic side pieces and the four gasket pieces, were assembled together to make the evaporator frame system. In order to align the gasket and the frame, each piece of the evaporator frame ordinarily had a groove in it so that the gasket could be fitted to the plastic. Then a sealant was applied to fill in cracks between the side frame members at the corners of the pan.
One function of the gasket, which generally was placed between the pan and frame, was to prevent water from getting between the plastic frame components and pan. The plastic frame could crack if water froze between the pan and frame.
In many cases, evaporator frame pieces are made using an injection molding process. Beads of plastic are fed into a hopper, melted, and injected under pressure into a mold. The hot viscous plastic (or melt) flows throughout the mold in seconds, racing through channels and merging again, until every nook and cranny is uniformly filled. Instantaneously, another short surge of hot plastic packs the already cooling mold to compensate for shrinkage and the flow shuts off. Cooling takes place in a few more seconds and the injection molding process is completed. The mold opens, and out comes the pieces for an evaporator frame.
A variety of problems are associated with the evaporator frames and gaskets currently in use. For example, one of the many problems associated with prior evaporator frame systems was the difficulty in arranging the gasket with the evaporator pan so as to form a proper seal. Further, because past evaporator frame systems were made of so many parts, they were inefficient and could take an extensive amount of time to assemble. For example, because the studs were too long, a portion of the studs used to connect the evaporator pan and frame routinely broke off after the nuts were placed on them. Yet, in the past, these long studs were necessary because the studs had to be long enough to fit into the gun that was used to weld them onto the pan.
Time and complexity was also added to the assembly process because the top and bottom plastic components required access holes for tools used to tighten the nuts. Further, the corners of the frame commonly had to be sealed with room temperature vulcanization silicon sealant (RTV) after the frame was assembled. The RTV was applied in the corners where the four plastic pieces abut and four gasket pieces abut against each other.
These and other disadvantages of the past are solved by the present invention.